Method of making and prescribing tinted lenses

ABSTRACT

Methods of fabricating and prescribing lenses suitable for color blindness and dyslexia correction are disclosed. The corrective lens may be formed of an optically transparent base material, which is tinted to a desired color for correction by immersion in a colorant dye. The color tinted lens is then tinted by a neutral tint dye to render the lens observable as a regular corrective lens. Prescription of such lenses may be based on a dynamically balanced, or haploscopic, fashion of prescription that comprises selecting a first visual filter from a set of sixteen filters and a second visual filter from the remaining set of fifteen filters, the first for the dominant eye and the second for non-dominant eye.

This is a divisional application of co-pending U.S. patent applicationSer. No. 13/076,756, filed on Mar. 31, 2011, which is acontinuation-in-part of U.S. patent application Ser. No. 11/827,893, nowU.S. Pat. No. 7,931,369, filed on Jul. 13, 2007.

BACKGROUND

Currently available techniques for correcting color discriminationresults in providing individually tinted lenses for a patient's eyes.The corrective lenses of different color tint indicate the purpose ofthe correction to observers and results in a cosmetically unacceptableappearance. To render the appearance more acceptable, U.S. Pat. No.6,089,712 discloses a lens of this type, where a central portion of thelens is tinted with the desired color correction for the individual eyeand the outer surface of the lens is coated with a mirrored reflectivematerial to make the color tinting invisible to an outside observer. Thetechnique described in the '712 patent provides the desired colorcorrection. However, the presence of the mirror reflective surface onthe lens has been found to be cosmetically unacceptable or impracticalto some. The mirrored surface may reflect such a high percentage oflight that the spectacles may produce an image that is too dark for thewearer. In a certain environments, such as offices or spaces withinsufficient light, wearing mirrored glasses may be ineffective and,perhaps, even inappropriate.

In the field of ophthalmology, it has been found that by providinglenses which selectively filter the incident light in the visible regionof the spectrum, e.g., from about 650 nm (red region) to 475 nm (blueregion), particularly in the shorter (blue) wavelengths, the lightreceived through the lens is thereby modified so as to affect the mannerin which it is handled neurologically, by the viewer. Lenses have beenproduced for patients suffering from color blindness which areindividually color tinted for the characteristics of a patient's vision.Such corrective lenses enable the patient to train their opticaldiscernment to perceive colors correctly and also to address many of thesymptoms of dyslexia.

SUMMARY

Thus, it is desired to provide color corrective lenses for patients withcolor blindness or dyslexia to treat the disability but in which thecolor tints are not discernible to an outward observer and which are notprohibitively costly. According to the methods disclosed herein, fittingof haploscopic filters helps re-synchronize and selectively change thewavelength of each color going into both eyes in a dynamically balancedformat. The use of different colors effectively changes the speed of theinformation in the brain's neurological pathways to enable sufferers ofdyslexia or color blindness to improve their reading ability,handwriting, and comprehension. The haploscopic filters disclosed hereinwork by changing the wavelengths of each color going into one or botheyes, which enhances color perception and color discrimination.

The present invention relates to the lens prescription and fabricationarts. It finds particular application in connection with improving colorperception for patients who are color deficient, or color blind as it iscommonly known, and for alleviating symptoms of dyslexia through acolored lens prescription. They may also be used to improve the ease ofreading for those with reading difficulties due to dyslexia or similardisorders. Furthermore, lenses fabricated or prescribed according to themethods disclosed herein may have an application in some neurologicaldiseases, including multiple sclerosis, and also in the partiallysighted. Among the benefits are improved productivity, function, readingspeed and ability, environmental and social adaptability, improvement inself-esteem and overall well-being in patients.

Although the lenses fabricated according to the methods disclosed hereinrestrict what portions of the visible spectrum are transmitted, they arenot colored in the conventional sense. While they function in a similarway to colored lenses, they do not physically appear colored to outwardobservers, or non-wearers. The lenses are tinted so as to appear neutralto such observers. Although the outward appearance of a certain color isproduced by reflecting light in a portion of the visible spectrum, aneutral appearance or a photo-grey effect, as in the disclosed lenses,is produced by a lens reflecting light equally across the spectrum.Thus, while the clinical element of the lens—the color correction—isretained and the lens functions as a colored lens, to outward observersthe lens will appear to have a neutral look. This is a desired effectboth clinically and cosmetically, because according to the methodsdisclosed herein, although the lenses worn by a patient are differentfor each eye and may employ different color correction, they appear verysimilar or identical to outward observers.

The methods of the present disclosure thus give a unique way ofcorrecting color blindness in a patient in a manner that disguises thecolor correction and provides the appearance of regular lenses. Themethods of the present invention may be applied to a variety ofophthalmic lenses (lenses though which light is transmitted into aperson's eye), including spectacle lenses, soft or rigid contact lenses,clip-on lenses, and binoculars, or other devices using lenses. Theophthalmic lens may also have a prescriptive correction or beuncorrected. It is to be appreciated that the exemplary lensprescription and fabrication methods are not limited to suchapplications and may find other applications and apply to other purposesfor the selective adjustment of light transmission through a lens.

In accordance with one aspect of the exemplary embodiment, a method offabricating an ophthalmic lens which may be used for correction of colordiscrimination of a patient, includes forming a lens of relatively openmolecular structure material, tinting the lens to a desired correctivecolor with ophthalmic dye capable of penetrating the lens molecularstructure and dyeing the lens with a dye having a neutral appearing tintcapable of penetrating the lens molecular structure.

In another aspect, a method of forming an ophthalmic lens includesinfiltrating a light filtering material into a body in the shape of thelens, thereafter, infiltrating a mask material into the body, to providea ratio of a concentration of the mask material to a concentration ofthe light filtering material which is higher in a first region of thebody than in a second region of the body further from a front surface ofthe body than the first region, whereby the mask material masks a tintimparted to the body by the light filtering material.

In yet another aspect of an exemplary embodiment, a method ofprescribing ophthalmic lenses is provided. Such method includes thesteps of determining a dominant eye from a first eye and a second eye,presenting each lens from a first set of lenses to the dominant eye ofthe patient, selecting a first optimum lens for the dominant eye fromthe first set of lenses, introducing each lens from a second set oflenses to the non-dominant eye of the patient, wherein the second set oflenses is the first set of lenses without the first optimum lens,choosing a second optimum lens for the non-dominant eye from the secondset of lenses, and fabricating an apparatus with the first optimum lensand the second optimum lens for wearing by the patient.

In still another aspect of an exemplary embodiment, a method of treatinglenses is provided. Such method includes the steps of saturating a lensbody with light filtering material and tinting an outward lens surfacewith mask material which causes the outward lens surface to appearneutral in color to observers. These as well as other aspects andadvantages will become apparent to those of ordinary skill in the art byreading the following detailed description, with reference whereappropriate to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of a method of the present disclosure;

FIG. 2 is a flow diagram of another method of the present disclosure;

FIG. 3 is a cross-section of a portion of a lens of the presentdisclosure;

FIG. 4 is an exemplary embodiment configured with spectacles; and,

FIG. 5 is an exemplary embodiment configured as a contact lens.

DETAILED DESCRIPTION

The present disclosure relates to a lens and to a method of making andprescribing such lenses. The lenses may be used for correcting theinability of a person to perceive colors properly or color blindness orto alleviate many of the symptoms of dyslexia in a patient. Theexemplary lens filters light transmitted through the lens to providefiltered light which is tailored to the patient's vision. The lens mayinclude an optically transparent base material in which a lightfiltering material is dispersed. The light filtering material may be acolor tint dye or combination of two or more color tint dyes.

The light filtering material is not visible to an outward observer. Itsappearance is masked by a masking material. The masking material maycomprise a neutral tint dye, e.g., one with a slight blue, brown, orgray tint. The masking material may be dispersed in the base materialand is preferably concentrated more highly toward the surface of thelens. As a result, the neutral tint predominates, masking any filteringmaterial to the outward observer.

To determine the precise color tint dye or combination of dyes to beused, a patient undergoes a fitting procedure whereby, with both eyesopen, lenses are held one at a time over the dominant eye while thepatient looks at written material, with the patient choosing thepreferred lens by a forced choice system. Then, with the chosen lensover the dominant eye and both eyes open, the remaining lenses are shownto the patient, and the patient is forced to choose the preferred lensfrom the remaining lenses for the second eye.

In one aspect of the exemplary embodiment, different lenses withdifferent color tints may be provided for each eye. However, each lensis such that the color corrective tint is not visible to an outsideobserver, resulting in a lens that is substantially indistinguishablefrom ordinary or vision-correcting lenses.

Referring to FIG. 1, an exemplary method of prescribing a lens with theproper color correction involves giving a subject a reading speed andaccuracy assessment test. This assessment may be according to theWilkins Rate of Reading test, which is well known and documented in theart. As a preliminary part of the assessment, it is also desired thatthe dominant eye be determined in binocular patients at step 60.Binocular patients are individuals who engage both eyes. In practice,this determination may be made using a free choice system. To that end,an apparatus such as a telescope may be used. The telescope may be asimple, one-foot tube constructed of cardboard or heavy paper, oranother similar device. The patient may then be directed to view adistant object monocularly through the telescope. The subject, given afree choice, will choose to hold the telescope to its dominant eye.Whichever eye the subject chooses to look through the telescope isrecorded as the dominant eye. The subject is then given randomized texton which to focus at step 62. The text may be printed on a sheet ofpaper, projected onto a wall, or otherwise provided to the patient. Thenwith both eyes open and focusing on the text that is presented to thesubject, preferably in front, the subject is shown a series of sixteencolored lenses, in paired fashion, over the dominant eye only, and askedto choose the preferred lens at step 64. Thus, the subject goes througheach lens in the series of sixteen lenses and picks the lens that isoptimum for the dominant eye. Each lens is preferably presented to thesubject in paired fashion, that is, in pair with another lens in theseries. The lenses are selected from equidistant points across thevisible spectrum. That is, the lenses used for the diagnostic settransmit light at approximately sixteen (16) equally spaced pointsacross the visible spectrum, approximately 390 nm to 750 nm althoughthere is a slight bias toward the shorter (blue) end of the visiblespectrum.

Then, with the optimum lens over the dominant eye and with both eyesopen, the subject is shown each of the remaining fifteen colored lensesin the series over the non-dominant eye at step 66. The remainingfifteen lenses may, likewise, be presented to the subject in a pairedfashion. And the subject will, again, make a forced choice as to theoptimum lens in the series of lenses for the non-dominant eye. Finally,the subject will repeat the reading speed and accuracy assessment atstep 68 and the result will be compared with the original result at step70. Thus, according to an exemplary embodiment of prescribing a lenswith proper color correction, each eye will have a different optimumlens from the series of sixteen colored lenses.

A commercially available diagnostic set of sixteen lenses may be usedfor such assessments. The spectral transmission of each lens determinesits unique characteristics but the lenses may be labeled withcorresponding numbers or codes to be easily differentiated. For example,a diagnostic set may have the following lenses:

Transmission Wavelength Lens Code 1 400 nm V100 2 650 nm O100 3 550 nmY100 4 480 nm A100 5 730 nm M100 6 700 nm P100 7 550 nm G100 8 450 nmB100 9 430 nm B200 10 460 nm B300 11 440 nm B400 12 610 nm Y200 13 560nm G200 14 420 nm V200 15 520 nm G200 16 680 nm R200

An exemplary method of making a lens according to the present inventionprovides for tinting a corrective lens of sufficiently open or spacedmolecular structure to provide the desired color correction. To tint alens, or to allow the absorption of color tint dye into a lens, the dyemay be heated. Whether or not a dye needs to be heated and for how long,depends largely on the particular dye used. Commercially available dyesthat require heating come with instructions for heating and appropriatetemperatures; usually, the dye is heated to 80° C. or higher. The colortint dye acts as a filtering material in the lens. The color tinted lensmay then be dyed with a neutral tint dye to give it the outwardappearance of an ordinary lens, or of a lens which is lightly tinted asin a pair of sunglasses.

In an exemplary embodiment according to the present invention, the colortint dye is heated according to the process described immediately above.The heated dye, in turn, heats the lens when the lens is brought incontact with the heated dye. For example, the lens may be immersed inthe dye. The duration of the immersion primarily depends on the color,material and thickness of the lens, among other factors. Thickness isusually dictated by the refractive power of the lens; higher powerlenses are thicker. The average immersion time is seven (7) to fifteen(15) minutes. The lens is thus heated to a suitable temperature forpenetration of the color tint dye, typically about 93° C. to 96° C.(200° F. to 205° F.). Heating the lens allows the lens to becomepermeable to the color tint dye. The same procedure is then repeated forthe neutral tint dye. Once the lens has cooled down, typically about two(2) minutes, it is brought in contact with neutral tint dye, which mayalso be heated. Heating neutral tint dye follows the same process asthat described above with reference to color tint dye. The neutral tintdye works as a mask material to mask the color corrective properties ofthe lens to an outside observer. The rate of penetration of the dyedepends largely on the dye concentration, temperature of the dye, andthe length of time the lens is exposed to the dye.

Other methods of infiltrating the filtering material and mask materialare contemplated. In another aspect of the present invention, thefiltering material and mask material are sequentially infiltrated intothe lens base material under vacuum or by lamination.

The filtering material (color tint dye) may be any suitable material formodifying the transmittance spectrum of visible light transmittedthrough the lens. In general, the visible spectrum ranges from about 400to 700 nm. The filtering material may be one which modifies thetransmission of light in at least a region of the spectrum between 400nm and 700 nm, e.g., by selectively absorbing a predominant portion ofthe light within a selected wavelength range of the visible spectrum(e.g., the filtering material prevents transmission of at least 50% ofthe light in the selected wavelength range). A lens comprising thefiltering material may transmit substantially all light in wavelengthsthat are outside the selected range (e.g., at least 80% of the lightoutside the selected range is transmitted). The filtering material maycomprise a color tint dye with a peak light absorption within the650-475 nm range, such that light transmitted by the lens has a red,blue, or green cast when viewed by an ordinary observer who does notsuffer from color blindness.

However, for a person with color blindness, the modified light allowsthe patient to view certain colors more easily. For example, in the caseof a lens which incorporates a red-transmitting filtering material, thelight transmitted may have a transmittance cut off at about 600 nm, withwavelengths from about 600-650 nm being predominantly transmitted andwavelengths from about 450-600 nm being predominantly filtered out. Thefiltering material may give the lens a colored tint that would beclearly apparent to an outside observer (in the absence of the maskmaterial). In the exemplary embodiment, the filtering material isformulated as a penetrant, that is, one which is able to penetrate themolecular structure of the lens body during fabrication. To act as apenetrant the molecules of the dye selected as the filter material maybe finely dispersed in a liquid carrier material, such as a solvent, andbe of sufficiently small size to penetrate the molecular structure ofthe lens body. Heating the mixture of the solvent and dye facilitatesthe penetration of the filtering material into the lens.

The mask material may be a neutral tint dye which is substantiallytransmissive, that is translucent enough to transmit a significantpercentage of incident light, about 60 percent or more, throughout thevisible range of the spectrum. In particular, the neutral tint materialis one which absorbs light generally evenly over the entire visiblerange (for example, transmits at least about 80% of the light atwavelengths between 450 and 650 nm).

In the exemplary embodiment, the mask material is formulated as apenetrant, that is, one which is able to penetrate the molecularstructure of the lens body during fabrication. It is also contemplatedby an exemplary embodiment that the lens may be heated before the maskmaterial is applied, thereby becoming more permeable to the particles ofthe mask material. Likewise, the mask material may be heated, too.

In accordance with an exemplary embodiment, it is preferable that themask material be concentrated near the outside of the lens. Byconcentrating the mask material near the outside of the lens, the tinteffect of the filtering material is masked to an outside observer andthe lens has an appearance of a regular lens. Thus, although the lensrestricts transmission of certain portions of the visible spectrum, thelens is not colored in a conventional way. It functions in a similar wayto ordinary colored lenses but it does not appear colored to an outwardobserver, because it has been treated to appear neutral. Outwardappearance of a certain color is produced by reflecting light in aportion of the visible spectrum; a neutral outward appearance or aphoto-grey effect is produced by the lens reflecting light equallyacross the spectrum. This allows for provision to subjects of two lensesthat appear neutral and, moreover, substantially similar to each other,even when the underlying color corrective property in each of the lensesis different and achieved by using differently colored filter materials.

The neutral tint that is selected as the mask material may have a slightblue, grey, or brown cast when viewed by an outside observer with normalsight, depending on the particular neutral tint that is selected. Themask material is present in the lens at a sufficient concentration tomask any color tint introduced by the filter material. In this way, apair of lenses worn by a patient, one of which incorporates a filteringmaterial which transmits light predominantly in a first, for example,the red region, and the other which transmits light in predominantly asecond, for example, the green region of the visible spectrum may havesubstantially the same neutral tint appearance to an outside observer.

Exemplary color tint dyes for correcting color blindness are well known,and disclosed, for example, in U.S. Pat. Nos. 3,586,423; 3,701,590;4,998,817; 6,089,712; and 7059719. Exemplary color tint dyes include azodyes, catalytic (reactive) dyes and sulfur dyes and those which arepermitted for use in contact lenses by the FDA. Exemplary neutral tintdyes include those used in the formation of sunglasses and those whichare permitted for use in contact lenses by the FDA.

Furthermore, according to an exemplary embodiment, water-based dyes maybe used as masking and/or filtering material. In the case of water-baseddyes, the dyes selected for the mask material and filtering material maybe hydrophobic to enable the dye molecules to preferentially enter thelens base material, as opposed to remaining in the water in which thedye is mixed. Such dyes may be heated to facilitate their penetrationinto the lens. Additionally, suitable catalytic dyes for use as thefiltering material and mask material may be obtained from Brain PowerInternational, Worcestershire, England.

In accordance with an exemplary embodiment of the present invention,exemplary base materials which may be used for the lens includeoptically transparent polymeric materials, such as, for examplediethylene glycol bis(allyl carbonate), widely known as CR39®composition, polycarbonate, Perspex, combinations thereof, or other lensforming materials. In some embodiments, the base material is one whichallows penetration of the filtering material and/or masks material bydiffusion and retains the infiltrated materials within the basematerial. The base material may form a chemical bond with the filterand/or mask material or otherwise hold the molecules of the dye withinits three dimensional structure. In general, glass does not permitpenetration of filtering materials and mask materials from liquid dyesolutions.

In the case of contact lenses, the polymeric material may comprise anysuitable lens forming polymer. Such as hydrogel copolymers, which arecross linked polymeric systems that can absorb and retain water in anequilibrium state. Hydrogel copolymers are generally formed bypolymerizing at least one hydrophilic monomer and a crosslinking agent.Representative, hydrophilic monomers include: unsaturated carboxylicacids, such as methacrylic acid and acrylic acid; (meth)acrylicsubstituted alcohols, such as 2-hydroxyethylmethacrylate and2-hydroxyethylacrylate; vinyl lactams, such as N-vinyl pyrrolidone; and(meth)acrylamides, such as methacrylamide and N,N-dimethylacrylamide.Typical crosslinking agents include polyvinyl, typically di- ortri-vinyl monomers, such as di- or tri(meth)acrylates ofdiethyleneglycol, triethyleneglycol, butyleneglycol and hexane-1,6-diol;and divinylbenzene. A specific example of a hydrogel-forming monomermixture is polymacon, composed primarily of 2-hydroxyethylmethacrylatewith a small amount of diethyleneglycol dimethacrylate as a crosslinkingmonomer. Optionally, the monomer mixture may include asilicone-containing monomer in order to form a silicone hydrogelcopolymer. Examples of silicone-containing monomers include: monomersincluding a single activated unsaturated radical, such asmethacryloxypropyl tris(trimethylsiloxy)silane, pentamethyldisiloxanylmethylmethacrylate, tris(trimethylsiloxy)methacryloxy propylsilane,methyidi(trimethylsiloxy)methacryloxymethyl silane,3-[tris(trimethylsiloxy)silyl]propyl vinyl carbamate, and3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate; andmultifunctional ethylenically “end-capped” siloxane-containing monomers,especially difunctional monomers having two activated unsaturatedradicals. See, for example, U.S. Pat. No. 7,147,326. Many otherlens-forming monomers and specific copolymers thereof are well known inthe art and are contemplated by this invention.

In an exemplary embodiment, the dye to be used as the filtering materialand/or mask material may be infiltrated into the base material of thelens from a solution of the dye in a suitable solvent, such as water oran organic solvent. In other embodiments, the filtering material may beincorporated into the lens material during polymerization of the lensmaterial.

Referring to FIG. 2, a method of fabricating the corrective lens isshown by way of example. A corrective lens body for the particularpatient's eye is formed at step 10 of an ophthalmic quality transparentbase material by any of the techniques known in the art of lens making.The lens may be formed as a spectacle lens or, alternatively, may beformed as a soft or hard contact lens. In some embodiments, the lens maybe machined or otherwise shaped to provide a refractive correction, suchas a prescriptive correction for short or long sight. In someembodiments, the lens may be formed without any prescriptive correction.

The method then proceeds to step 12 and the dye or solution thereof isheated to a suitable temperature for infiltration of the color tint dye,e.g., a temperature of about 95° C. (205° F.)−118° C. (295° F.). Then,at step 14, the lens base is tinted to the desired corrective color withthe color tint dye. The rate of penetration of the dye and/or the amountof the dye which the base material is able to take up may be increasewith increasing temperature. In general, the temperature is selected tobe below a temperature at which the lens may be damaged through warping,melting or other deformation and below the boiling point of any solventin which the dye is incorporated. The lens is immersed in the heatedcolor tint dye or otherwise contacted therewith for a sufficient periodof time for the dye to infiltrate the base material, such as about 15-30minutes.

The dye that is selected depends on a specific wearer and his specificcolor blindness, that is, it depends which colors are being filteredout. Some color tint dyes are readily available and others are a mixtureof two or more tints and need to be mixed by a lab technician. Aspectrophotometer may be used to assure the quality and consistency ofcolor. After the infiltration of the color tint dye into the lens body,the color tinted lens body is removed from the color tint dye and may beallowed to cool for a period of time sufficient for the lens to cure orotherwise fix the color tint dye within the lens body.

The lens may then be given a period of time to cool at step 16, usuallyabout two (2) minutes. Mask material is then applied to the color tintedlens. For this, the color tinted lens is tinted with a neutral tint dye.At step 18, the neutral tint dye (or solution thereof) may be heated,prior to immersing or otherwise contacting the lens with the neutraltint dye or solution thereof at step 20.

In one embodiment, the infiltration of the filtering material and/ormask material may be conducted at ambient pressure. In otherembodiments, the infiltration process may be conducted under a vacuum orby lamination.

Subsequent to the neutral tint dyeing of step 20, the lens is installedin spectacles if a spectacle lens has been made, or worn by the user, ifa contact lens was formed, in step 22.

In the case of two lenses to be worn as spectacles or contact lenses, adifferent filtering material for providing a different corrective colormay be used in each lens. In other embodiments, both lenses mayincorporate the same filtering material. The same mask material may beused in both lenses.

It is observed and, therefore, contemplated and described by the presentinvention at FIG. 2 that when the filtering material is permeated intothe base material of the lens, it penetrates into the base material fromthe surface of the lens to at least a first depth. However, thefiltering material may also penetrate the lens body entirely, if it isleft in contact with the dye for a longer period of time. Thereafter,when the mask material is permeated into the lens that was alreadytreated with the filtering material, the mask material remainspredominantly near the surface of the lens. This is because the filtermaterial particles that are already in the lens impede the penetrationof the mask material deep into the lens.

The concentration gradients of the mask and filtering materials in thetreated lens are thus different. For example, a ratio of theconcentration of the mask material to the concentration of the filteringmaterial may be higher nearer the surface of the lens than in a regionfurther from the surface of the lens. The concentration of the maskmaterial may be expressed as total moles of color tint dye per cc ofbase material. The concentration of the filtering material may beexpressed as total moles of the neutral tint dye per cc of basematerial.

Referring to FIG. 3, a portion of a lens, such as a spectacle lens orcontact lens, indicated generally at 30, includes an ophthalmic base 32formed of a base material with color tint dye molecules 34 dispersedtherein (indicated by a “−” sign). Neutral tint dye molecules 36(indicated by a “+” sign) are dispersed in the base material. Theneutral tint dye molecules are concentrated predominantly in one or bothof surface regions 38, 40 located adjacent opposed exterior surfaces 42,44 of the lens. Surface 42 is the rear surface of the lens 30 which isto be positioned closest to the patient's eye, while surface 44 is thefront surface of the lens to be positioned furthest from the patient'seye, and thus closest to an outside observer. As noted above, the colortint dye may be an ophthalmic dye with transmissibility of only adesired portion of the visible spectrum or desired chromaticity bandwhile the neutral tint dye may be an ophthalmic dye of eventransmissibility across the visible spectrum. The base 32 into which themask and filter materials are incorporated is integrally formed, as asingle piece, without lamination or coating, e.g., by molding,optionally followed by lathing or other shaping.

The color tint dye molecules 34 may be dispersed throughout the lensbase material 32 or may be predominantly in regions 46, 48, which arespaced from the lens surfaces by the surface regions 38, 40,respectively. The regions 38 and 40 are thus closer to the respectivefront and rear surfaces than the respective adjacent regions 46, 48.Regions 38 and 40 extend generally parallel with the respective surfaces42, 44. Although FIG. 2 illustrates these regions 38, 40 as containingonly the mask molecules 36, it is to be appreciated that this region mayalso contain some of the filter molecules 34, but generally too few, atleast near the surface, to impact the neutral tint appearance of thelens.

In the embodiment shown, a ratio of the concentration of the maskmaterial 34 to the concentration of the filtering material 36 is higherin region 40, nearer the surface 44 of the lens, than in adjacent region48, further from the surface 44 of the lens. Similarly, a ratio of theconcentration of the mask material 34 to the concentration of thefiltering material 36 may be higher in region 38, nearer the surface 42of the lens, than in region 46, further from the surface of the lens,although this is not required. In one embodiment, the concentration ofthe colorant dye 34 is higher in the second region 48 than in the firstregion 40 (and may also be higher in the region 46 than in region 38).The concentration of the neutral tint dye 36 is higher in the firstregion 40 than in the respective second region 48 (and optionally alsohigher in region 38 than in region 46). The desired variation inconcentration between the different dyes is achieved by heating the dyesseparately in separate tint baths and manipulating the duration of theimmersion of a lens in a dye (or other method of contacting a lens anddye) to reach the desired effect.

The distribution of the dye particles within a lens is controlled bytime or duration of immersion of the lens in the dye, the size of thedye particles, or the size of the lens matrix. Heating the lens causesthe lens to expand and facilitates absorption of the dye. The sequentialapplication of the dyes further helps to control the distribution of thedye. In the preferred embodiment, the color tint dye is applied beforethe mask material. Therefore, the saturation of the color tint dyeparticles in the lens prevents over-absorption of the mask material.Usually, the duration of immersion of a lens in color tint dye is longerthan duration of immersion in the mask material. Thus, in the exemplaryembodiment, there is a higher concentration of color tint dye in thelens body than at the surfaces. Likewise, there is a higherconcentration of mask material at the surfaces than in the lens body.

Referring to FIG. 4, a pair of lenses 60, 62 of different color tintaccording to the present disclosure are shown, in an exemplaryembodiment as mounted in a frame 64 forming spectacles indicatedgenerally at 66.

In another embodiment, the lens base 32 may be formed by lamination oflayers rather than as a single integral layer as shown in FIG. 2. Forexample, the lens may comprise a first base layer which incorporates theneutral tint dye and a second base layer, to be positioned closer to thewearer than the first base layer. The first base layer may be formed ina separate step from the second base layer, e.g., by forming the firstbase layer and laminating or coating the second base layer thereto, orvice versa. For example, a separate coating or lamination is applied toa lens for correcting color discrimination, such as a coating with aneutral color appearance, to disguise the underlying color tint of thecorrective lenses.

Referring to FIG. 5, an exemplary lens, such as a contact lens isindicated generally at 70 and comprises a front exterior surface 72,curved to be located furthest from the wearer's eye, a rear exteriorsurface 74, curved to be positioned closest to the wearer's eye and abody 76 intermediate the first and second surfaces. The lens bodyincludes a first region or layer 78, closest to the front surface and asecond region or layer 80, spaced from the front surface by the firstregion. A ratio of the concentration of the mask material 34 to theconcentration of the filtering material 36 is higher, on average, inregion 78, nearer the front surface 72 of the lens than in region 80,further from the front surface of the lens. Also, a concentration of thecolorant dye may be higher in the second region 80 than in the firstregion 78. A concentration of the neutral tint dye may be higher in thefirst region 80 than in the second region 78.

The present disclosure thus describes a unique low cost technique formaking lenses that may be used for correcting color blindness oralleviating symptoms of dyslexia in a patient, which lenses, when worneither as contacts or in spectacles, give the outward appearance ofneutral tinted lenses and the color correction is otherwiseindistinguishable from regular corrective lenses.

Various exemplary embodiments have been described above. Those skilledin the art will understand, however, that changes and modifications maybe made to those examples without departing from the scope of theclaims.

What is claimed is:
 1. A method of fabricating a lens comprising: (a)forming a lens from a material of relatively open molecular structure;(b) first, tinting the lens to a desired corrective color with anophthalmic dye, wherein the ophthalmic dye is heated to obtain a heatedophthalmic dye and the lens is immersed in the heated ophthalmic dye sothat the heated ophthalmic dye penetrates the lens molecular structure;and (c) second, dyeing the lens with a neutral dye that transmits about60% or more of incident light across the visible spectrum, wherein theneutral dye is heated to obtain a heated neutral dye and the lens isimmersed in the heated neutral dye so that the heated neutral dyepenetrates the lens molecular structure, such that the neutral dye isconcentrated primarily at surface regions adjacent exterior surfaces ofthe lens, and provides the lens with a neutral color appearance.
 2. Themethod defined in claim 1, wherein the step of dyeing includes dyeing asite remote from the site of tinting.
 3. A method of forming anophthalmic lens comprising: (a) forming a first layer of an ophthalmicmaterial; (b) heating an ophthalmic dye to obtain a heated ophthalmicdye; (c) immersing the first layer in the heated ophthalmic dye to tintthe first layer to a desired corrective color; (d) forming a secondlayer of the ophthalmic material; (e) laminating the second layer with aneutral tint dye that transmits about 60% or more of incident lightacross the visible spectrum to form the ophthalmic lens that appearsneutral in color to an observer.
 4. The method defined in claim 3,wherein the step of forming the first layer comprises forming the firstlayer of open molecular structure material.
 5. A method of treating alens, the lens including a lens body and an outward lens surface, themethod comprising: first, heating a light filtering material to obtain aheated light filtering material; second, immersing the lens body in theheated light filtering material for a period of time sufficient todistribute the light filtering material throughout the lens body; third,heating a mask material to obtain a heated mask material that transmitsat least 60% of incident light across the visible spectrum; fourth,immersing the lens body in the heated mask material to tint the lensbody to a desired neutral color so that the lens appears neutral incolor to observers.
 6. The method of claim 5, wherein the mask materialis concentrated at the outward lens surface.